Nail-gun narcolepsy nabbed by neuroscience

The rather painful X-ray to the left was taken from a 48-year-old patient who, it should be said immediately, survived his unfortunate encounter with a nail-gun and its 6-inch long projectile. But it’s what happened after the nail’s removal that merited the publication of this photograph in the medical journal The Lancet last month by University of Chicago doctors Babak Mokhlesi and Mohsin Khan.

Some time after the patient’s recovery from this very severe brain injury, he presented to the University of Chicago Sleep Disorders Center with hypersomnolence – sleeping, on average, 20 hours each day. The man’s sleep patterns were also unusual; he fell from the awake state into sleep faster, achieved REM sleep more rapidly than normal and woke up frequently during a 7-hour polysomnogram, or sleep test. Doctors were able to treat the man’s narcolepsy with methylphenidate (commonly known as Ritalin) and modafinil, two stimulants commonly prescribed to treat the disorder.

According to the article, the man’s hypersomnolence improved under medication. There was also a secondary side-effect of the gruesome injury – the man’s obsessive compulsive disorder “completely resolved.”

Briefly mentioned in the article’s brief text (that picture tells a thousand words, so there’s not much more to say) is that sleep disorders are commonly seen following traumatic brain injuries. They’re not really tied to specific brain areas; injury to any part of the brain often causes a sleep disorder. The conditions can arise from mild injuries (such as a concussion) or severe ones (such as a six-inch nail in the occipital lobe).

A recent review of traumatic brain injury literature found that between 30 and 70 percent of brain-injured patients experience some type of sleep disorder after the injury, usually insomnia. Oddly, patients with mild TBI were more likely to be diagnosed with sleep problems than those with severe injury (where our nail-gun patient would most likely fall), though the review authors speculate that could be because severe injury patients have more pressing issues, such as re-learning how to walk or talk.

As for hypersomnia, a 2007 study found that more than half of traumatic brain injury patients self-reported “sleepiness” one month after injury, and more than a quarter continued to report excessive daytime sleepiness a year later. At this 1 year mark, “those with more severe brain injuries reported greater sleepiness,” the authors reported. Another study found that 40 out of 87 TBI patients exhibited sleep disorders 3 months after the injury, and 5 of those were diagnosed with narcolepsy. That’s a 6% rate of narcolepsy, which compared to the estimated national rate of 1 in 2,000 (or 0.2%), certainly seems like a pattern.